The ecological importance of clean air is as evident as our need to breathe. Nevertheless, the demands of an industrialized society and the consequent burning of fuel for energy tends to compromise air quality. Existing fuels that are burned in boiler systems to produce steam for heating and power supply include distillate (number 2) fuel oil, residual (number 6) fuel oil, blended distillate and residual fuel oil, and coal. These fuels typically release substantial quantities of harmful pollutants, such as sulfur oxides, nitrogen oxides and carbon monoxide. Moreover, each of these fuels is subject to supply shortages as societal energy demands increase. In fact, dwindling mineral oil reserves are a primary factor in the ongoing energy-supply crisis.
Clean air legislation, such as the Clean Air Act in the United States, has been enacted to control the amount of various chemicals released into the atmosphere in an effort to protect human health and the environment. At a local or regional level, industry is typically regulated by state environmental protection agencies that set limits as to the amounts of airborne pollutants that can be emitted from a given facility.
Many existing energy sources, particularly mineral oils (e.g., petroleum-based fuels), release substantial amounts of pollutants, such as nitrogen oxides (NOx), sulfur oxides (SOx), carbon monoxide (CO) and particulate matter (PM) upon burning. These pollutants cause respiratory diseases, other human ailments and, over time, death. These pollutants also poison the environment via acid rain, ground-level ozone and greenhouse-gas-induced global warning.
As energy demands increase, the pressures, conflicts and costs involved in supplying that energy without exacerbating these health and environmental problems and in complying with clean air regulations become increasingly pressing.
Embodiments of the present invention are directed to methods for producing energy with substantially-reduced pollutant concentrations of NOx, SOx, CO, and PM in the resultant gaseous emissions. Moreover, these methods utilize, as an energy source, a byproduct of natural fatty-acid manufacturing.
The byproduct that is used in embodiments of the invention is a natural oil byproduct. The natural oil byproduct can be produced by vaporizing a natural fatty-acid composition from a feed composition including an animal fat and/or vegetable oil in a distillation process, wherein the feed composition is first hydrolyzed to remove glycerine. The feed composition (also referred to as a xe2x80x9cnatural oil compositionxe2x80x9d) can be in a rendered, crude or refined form. The natural oil byproduct can then be processed and burned, either alone or mixed with another energy source, to release energy that is then harnessed to drive a process, such as boiling water in the furnace of a boiler to produce steam.
The natural oil byproduct can include free fatty acid and unhydrolyzed fats/oils as primary constituents. The terms, xe2x80x9cfatxe2x80x9d and xe2x80x9coil,xe2x80x9d are generally used interchangeably herein. The term, xe2x80x9cfat,xe2x80x9d is generally used in reference to animal products, while the term, xe2x80x9coil,xe2x80x9d is generally used in reference to vegetable products. However, recitations of either xe2x80x9cfatxe2x80x9d or xe2x80x9coil,xe2x80x9d as in xe2x80x9cnatural oil byproduct,xe2x80x9d can refer to a byproduct of either animal fat or vegetable oil or a combination of the two. Likewise, recitation of an xe2x80x9cunhydrolyzed fat/oilxe2x80x9d refers to an unhydrolyzed animal fat, an unhydrolyzed vegetable oil or a combination of the two.
The natural oil byproduct can also include unsaponifiable impurities and oxidized, polymerized fatty materials, typically at concentrations that are substantially smaller than those of the free fatty acids and unhydrolyzed fats/oils. In one embodiment, the natural oil byproduct comprises about 20% to about 50% free fatty acid, about 20% to about 60% unhydrolyzed fat/oil, about 2% to about 5% unsaponifiable impurities and about 2% to about 7% oxidized, polymerized fatty materials, wherein all percentages are by weight. The fatty acid that is vaporized during distillation can be at least about 90% of the initial composition, by weight. Due to the nature of the natural oils from which it is derived, the natural oil byproduct, unlike byproducts of petroleum and other mineral oils, can be substantially free (allowing for trace impurities) of sulfur compounds, nitrogen compounds and volatile organic compounds. In particular embodiments, the natural oil can be coconut oil, soybean oil, canola oil, sunflower oil, linseed oil, tallow and animal greases.
The invention also resides in selling the natural oil byproduct to industry or to others for use as a fuel, the fuel providing the user with the surprising and previously-unrecognized benefits of reduced pollutant emissions.
By substituting the natural oil byproduct, in whole or in part, for another fuel (such as number 2 fuel oil, number 6 fuel oil, coal and combinations thereof), an energy producer can achieve a substantial decrease in the emission of nitrogen oxides, sulfur oxides, carbon monoxide and particulate matter. Particular advantages can be achieved by substituting the natural oil byproduct for the other fuel(s) in situations where a desired level of energy production cannot be achieved using only the other fuel(s) without violating pollutant-emission levels established by a regulatory agency. Pollutant-emission levels can be maintained at or below regulated limits by evaluating the respective emission concentrations from the natural oil byproduct and from the other fuel(s) and calculating the concentration ratio of the byproduct and the fuel(s) that will produce desired emission concentrations, wherein the resultant emission concentrations will be a proportional function of the respective emission concentrations for the different fuels.